Virtual reality adds a new dimension - immersion - to
graphics display. Moreover, the characteristics of this new
technology allow for a greater interactivity with the user.
The Virtual Water
project is a virtual environment applied to the learning and
teaching of Physics and Chemistry. The project involves aspects
as atomic and molecular orbits, electronic densities, bonds,
phase transitions, etc.
It is a
multidisciplinary work involving areas as computational
simulation of physical and chemical systems, computer graphics
and science education.
Partners of this
project are Centro de Computação
Gráfica, Coimbra, Exploratório
Infante D. Henrique, Coimbra, Physics Department of the Instituto
Superior Técnico, Lisboa, and High
Education School for Technology and Management, Guarda.

The recourse to
graphics, in particular to three-dimensional ones, for
visualizing and interpreting information has been increasing in
the research and teaching of sciences. In particular, that
recourse is needed in domains where the interpretation of complex
information is more demanding, as it happens in molecular
modelation. The reasons for such interest are clear: in
scientific research it is easier to obtain understanding from a
three-dimensional model than from the simple reading of numbers
or formulas; in the apprenticeship domain the utility of
graphical methods, in particular the immersive ones, is being
proved, for instance for forming correct conceptual models [1].
The Virtual Water
project aims at the conception of an educational environment,
joining molecular modelation with immersive three-dimensional
graphic representation. The choice of water is justified by the
fact that this is a common and relatively simple substance. Its
study has interested many investigators who do realistic
simulations of water in Physics, Chemistry and Biology [2,3]. However,
less attention has been given to the pedagogical exploration of
water simulations.
The subjects approached in the project go from the study of the
molecule geometry to the structures of the solid, liquid and
gaseous phases, through the study of the electronic density and
the chemical bonding by hydrogen bridges. The water model is
based on the SPC (Simple Point Charge) model. Since some studies
of water start with atomic orbits, in particular with the
hydrogen s, p and d, this subject is also
included in the project.

Macro => Micro - from the water phases to the
atoms (yellow line in the Figure 1);

Micro => Macro  from the atomic orbits
to the water phases (red line).

Figure 1 - Scheme of the environment Virtual
Water. The yellow line denotes the content exploration going
from the macroscopic to the microscopic side while the red line
denotes the exploration going from the microscopic to the
macroscopic side.

In any case, the
scenery exploration is preceded by navigation in a training
environment. The goal is to help the user to achieve good
adaptation to the interfaces (glove and Head Mounted Display),
navigation and interaction in virtual worlds.

The project is being done in two phases.

The first includes the visualisation
of some quantum mechanics aspects:

Figure 2  The ball-and-stick
geometry of the water. (Click here for the VRML format)

The molecular orbitals of the water (Figure 3). The orbital
concept is crucial to the student who is
exploring the nuances of atomic and molecular
structures.

Figure 3  The fourth occupied
molecular orbital of water from the Molecular Orbital Virtual
Scenery. Calculations have been performed with "PC Gamess"
(a program for ab initio quantum chemistry) and
visualisation with "Molden" (a package for displaying
molecular densities). (Click here for the VRML
format)

Figure 4  The electronic
density of the water. Calculations have been performed with
"PC Gamess" (a program for ab initio quantum
chemistry) and visualisation with "Molden" (a package
for displaying molecular densities). (Click here for the VRML format)

Figure 7  a frame of the phase
liquid molecular dynamics of the water.

gaseous phase

phase transitions

vibrations.

Since in many cases quantum effects in the
dynamics of the atoms is small, The molecular dynamics on Virtual
Water is an ab initio simulation based on Lennard-Jones
potential and Newtonian mechanics. With the increased speed and
availability of computing resources, it is coming more and more
common to model systems atom by atom, moving each atom or
molecule in response to the forces acting on it. Many experiments
give insight into the structure and dynamics of water, but there
are strong limitations to the general use of these experiments.
For one thing, the experimental apparatus are expensive. Second,
not all desired state points of the phase diagram of water are
easily accessible. For example, it is very difficult to do
experiments at the critical point of water, or with super heated
or super cooled water. From simulations like these one can better
interiorize microscopic models and better understand the
substance's behaviour.

For implementing
the virtual environment we use the WorldToolkit software
that serves the definition and creation of the virtual scenarios
and the following hardware: two PC's with Pentium II at 300 MHz,
with 128 Mb of RAM, in network, using an accelerator graphic
board Matrox Millennium II AGP with 8 Mb of RAM. For the
navigation and immersion in the virtual environment, we use the
Head Mounted Display V6 from Virtual Research, as well as
one Cyberglove from Virtual Technologies and a
position sensor to two receptors, Isotrack II, from Polhemus
(Figure 8).

Figure 8  The virtual reality
hardware used on virtual water project

The final product of this work will be disposed to the school
community through the Competence Center "Nónio-Softciências".

The use of graphics is, indeed, a powerful tool for
visualizating and understanding of complex and/or abstract
information. The immersion capacity is a recent aspect to be
explored and evaluated. A virtual environment for the teaching of
Physics and Chemistry is being developed to test the possibility
of applying virtual reality in teaching and learning. The work is
in a preliminary phase of execution, so that its evaluation
cannot yet be done.

The authors thanks Prof. Doctor Victor Gil, from the Chemistry
Department of the University of Coimbra, for his suggestions, and
Prof. Doctor José Carlos Teixeira, from the Computer Graphics
Center of the same University for equipment and software
facilities.